JP2009076242A - Magnetron - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetron in which, while maintaining a heat resistance and a vacuum holding performance inside a magnetron, choosing options of end hat materials are increased. <P>SOLUTION: A pair of end hats 6, 7 fixed on both ends of a cathode 5 of the magnetron which is provided with an anode cylinder 1 extending along a central axis 41 in a cylindrical shape, a plurality of vanes 2 extending toward the central axis 41 from inside the anode cylinder 1, and the cathode 5 of a spiral shape arranged on the central axis, are made of a niobium containing metal, such as a niobium simple substance, a Nb-Sn alloy, a Nb-Ti alloy, a Nb-Ni alloy or the like. On a surface of the end hats 6, 7, a gas absorbing metal such as Ta, Zr, Ti or the like may be deposited. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a magnetron used in a microwave oven or the like.

A general magnetron includes an anode cylinder and a plurality of vanes. The vanes are arranged radially inside the anode cylinder. The vanes are connected to each other in the circumferential direction by a pair of large and small strap rings brazed to the upper and lower ends of the vane. In the electron action space surrounded by the free ends of the plurality of vanes, a spiral cathode is disposed along the axis of the anode cylinder. Both ends of the spiral cathode are fixed to the output side end hat and the input side end hat, respectively. Further, a substantially funnel-shaped output side and input side pole piece are fixed to both ends of the anode cylinder, respectively. The end hat is made of, for example, molybdenum (see, for example, Patent Document 1).
JP 2006-351350 A JP 2000-306518 A

  The inside of the magnetron is maintained at a high vacuum. For this reason, a getter that adsorbs gas is provided inside the magnetron. In a general magnetron, a getter is obtained by sintering a gas adsorbing metal such as titanium or zirconium on the surface of an end hat (see, for example, Patent Document 2). Further, since the vicinity of the cathode becomes high temperature during the operation of the magnetron, a general magnetron uses a high melting point molybdenum or the like as a support rod for supplying current to the end hat or the cathode.

  However, molybdenum, zirconium, and titanium are so-called rare elements, and when used as getters, the manufacturing method is complicated. Therefore, alternative materials for magnetron parts should be selectable. This is important from the viewpoint of the diversity of material supply.

  Therefore, an object of the present invention is to increase the choice of materials for the end hat and the support rod while maintaining the heat resistance and vacuum holding performance inside the magnetron.

  In order to solve the above-described problems, the present invention provides a magnetron, an anode cylinder extending in a cylindrical shape along a central axis, a plurality of vanes extending from the inner surface of the anode cylinder toward the central axis, and the central axis A spiral cathode disposed on the cathode, a pair of end hats fixed to both ends of the cathode, and a support rod connected to each of the end hats for supplying a current to the cathode. At least one of the hat and the support rod is formed of a metal containing Nb.

  ADVANTAGE OF THE INVENTION According to this invention, the choice of the material of an end hat or a support rod can be increased, maintaining the heat resistance and vacuum holding | maintenance performance inside a magnetron.

  Embodiments of a magnetron according to the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same or similar structure, and the overlapping description is abbreviate | omitted.

  FIG. 1 is a longitudinal sectional view of an embodiment of a magnetron according to the present invention.

  The magnetron of the present embodiment includes an anode cylinder 1, a cathode 5, a pair of end hats 6, 7 and a pair of pole pieces 8, 9 arranged along the same axis (center axis 41), and the center axis. A plurality of vanes 2 extending radially from the vicinity of 41 are provided.

  The anode cylinder 1 extends in a cylindrical shape along the central axis 41. The vane 2 extends radially from the vicinity of the central axis 41 and is fixed to the inner surface of the anode cylinder 1. The vanes 2 are each formed in a substantially rectangular plate shape. The free end 31 of the vane 2 on the side not fixed to the inner surface of the anode cylinder 1 is disposed on the same cylindrical surface extending along the central axis 41, and this cylindrical surface is referred to as a vane inscribed cylinder. The plurality of vanes 2 are connected to each other in the circumferential direction by strap rings 3 and 4 that are paired in large and small brazed to the upper and lower ends of the vane.

  The cathode 5 has a spiral shape and is disposed inside the vane inscribed cylinder, which is an electron action space, and is disposed on the central axis of the anode cylinder 1. Further, both ends of the cathode 5 are fixed to the end hats 6 and 7, respectively. The end hats 6 and 7 are disposed outside the central axis 41 with respect to the vane 2. The antenna-side (output-side) end hat 6 is formed in a cup shape opened toward the cathode 5, and the stem-side (input-side) end hat 7 is formed in a ring shape with niobium (Nb).

  The pair of pole pieces 8 and 9 are each formed in a funnel shape having a through hole 32 at the center. The center of the through hole 32 is located on the central axis 41. Each pole piece 8, 9 is formed so as to spread from the through hole 32 toward the outside of the central axis 41 with respect to the space sandwiched between the end hats 6, 7. The outer diameters of the end hats 6 and 7 are formed substantially the same as the diameter of the anode cylinder 1. The outer peripheral portions of the end hats 6 and 7 are fixed to both ends of the anode cylinder 1, respectively. Further, the pair of pole pieces 8 and 9 are arranged with a space between the end hats 6 and 7 interposed therebetween.

  Further, cylindrical metal sealing bodies 10 and 11 are fixed to the pole pieces 8 and 9, respectively. Each metal sealing body 10, 11 is also in contact with one end of the anode cylinder 1.

  An output-side ceramic 12 is joined to the end of the output-side metal seal 10 opposite to the pole piece 8. An exhaust pipe 13 is joined to the end of the output side ceramic 12 opposite to the metal seal. An antenna 14 is derived from the vane 2. The antenna 14 passes through the output-side pole piece 8, extends in the output portion, and the tip is clamped and fixed by the exhaust pipe 13. The entire exhaust pipe 13 is covered with a cap 15.

  An input-side ceramic 16 is joined to the end of the input-side metal seal 11 opposite to the pole piece 9. Two support rods 17 and 18 are connected to the cathode 5 via end hats 6 and 7. The support rods 17 and 18 are led out of the pipe through, for example, the relay plate 19 and connected to the input terminal 20.

The inside of the magnetron in which the cathode 5 and the like are arranged is kept in a vacuum state of about 10 ⁻³ to 10 ⁻⁴ Pa, for example.

  Further, the magnets 21 and 22 and the yokes 23 and 24 are disposed so as to surround such an oscillating unit main body to form a magnetic circuit. Further, an exterior is formed by a radiator 25 for cooling the oscillation unit main body, a filter 26 connected to the input side, and a box 27 surrounding the filter 26.

  In the magnetron of the present embodiment, end hats 6 and 7 are formed of niobium. That is, as the end hat material, it is possible to select a material other than molybdenum (Mo) used in a general magnetron. Niobium has a melting point of about 2470 ° C., which is almost equivalent to the melting point of molybdenum of about 2620 ° C. from the viewpoint of a margin for the temperature during operation of the magnetron. Furthermore, since niobium is a gas adsorbing metal, it can have gas adsorption performance equivalent to an end hat in which titanium is fixed to the surface of molybdenum. Therefore, in the magnetron of the present embodiment, a new end hat material called niobium can be selected while maintaining the heat resistance and vacuum holding performance inside the magnetron.

  The end hats 6 and 7 can be formed by pressing a niobium plate. For this reason, the process of electrodeposition and sintering of a gas adsorption metal is unnecessary, and manufacturing cost can be reduced.

  Further, the material of the end hats 6 and 7 may be not only a metal of niobium alone but also an alloy containing niobium. For example, the end hats 6 and 7 may be formed of a niobium-tin alloy (Nb—Sn), a niobium-titanium alloy (Nb—Ti), or a niobium-nickel alloy (Nb—Ni) alloy. Even when these alloys are used, the end hats 6 and 7 have gas adsorption performance. When such an alloy is used, the melting point will be lower than that of niobium alone, but by setting the ratio of the alloy components in an appropriate range, a sufficient margin for the temperature during operation of the magnetron is ensured and appropriate heat resistance is ensured. can do.

  As described above, by using the niobium-containing alloy for the end hats 6 and 7, it is possible to further increase the options of the end hat material while maintaining the heat resistance and vacuum holding performance inside the magnetron.

  Further, another gas adsorbing metal may be fixed to a part or all of the surfaces of the end hats 6 and 7. The gas adsorbing metal can be fixed by, for example, forming the end hats 6 and 7, electrodepositing the gas adsorbing metal, and then sintering. As the gas adsorption metal, for example, tantalum (Ta), zirconium (Zr), titanium (Ti) can be used.

  By adhering a gas adsorbing metal to the surfaces of the end hats 6 and 7 made of niobium or a niobium alloy, the gas adsorbing capacity can be appropriately increased. In particular, when a gas adsorption metal having a gas adsorption operation temperature different from that of niobium is fixed, the gas adsorption operation temperature range can be expanded. For example, the gas adsorption operating temperature of niobium is in the range of about 400 ° C. to about 900 ° C. On the other hand, the gas adsorption operating temperature of titanium is in the range of about 500 ° C. to 1200 ° C. Therefore, by adhering titanium to the surface of the end hats 6 and 7 made of niobium or niobium alloy, the gas adsorption operation temperature can be expanded to a range of about 400 ° C. to about 1200 ° C. For example, the end hat 6 on the output side may be 900 ° C. or higher during operation of the magnetron. However, the gas adsorbing performance can always be maintained during operation of the magnetron by fixing the gas adsorbing metal to the output-side end hat 6 even at 900 ° C. or higher.

  Niobium or a niobium alloy has gas adsorption performance. Therefore, even when the gas adsorbing metal is fixed to the end hats 6 and 7, it is fixed as compared with the case where the end hat is formed of a material that does not adsorb gas such as molybdenum and the gas adsorbing metal is fixed to the surface of the end hat. The amount of gas adsorbing metal is small.

  Further, the support rods 17 and 18 located in the vicinity of the cathode 5 become high temperature during operation of the magnetron, and thus may be formed of molybdenum which is a refractory metal. The support rods 17 and 18 can also be formed of niobium or a niobium alloy if the temperature during operation of the magnetron has a margin with respect to the melting point of niobium. In this case, since the support rods 17 and 18 also function as getters, the degree of vacuum inside the magnetron can be further increased. When the temperature of the support rods 17 and 18 during the operation of the magnetron exceeds the gas adsorption operation temperature of niobium (in the range of about 400 ° C to 900 ° C), titanium that supports gas adsorption in a higher operation temperature range is supported. You may fix to the surface of the rods 17 and 18.

  The above description is merely an example, and the present invention is not limited to the above-described embodiment, and can be implemented in various forms.

It is a longitudinal cross-sectional view in one Embodiment of the magnetron based on this invention.

Explanation of symbols

1 ... anode cylinder, 2 ... vane, 3 ... strap ring (large), 4 ... strap ring (small), 5 ... cathode, 6 ... end hat (output side), 7 ... end hat (input side), 8 ... pole Piece (output side), 9 ... Pole piece (input side), 10 ... Metal sealing body (output side), 11 ... Metal sealing body (input side), 12 ... Output side ceramic, 13 ... Exhaust pipe, 14 ... Antenna, 15 ... Cap, 16 ... Input side ceramic, 17 ... Support rod, 18 ... Support rod, 19 ... Relay plate, 20 ... Input terminal, 21 ... Magnet, 22 ... Magnet, 23 ... Yoke, 24 ... Yoke, 25 ... Radiator, 26 ... Filter, 27 ... Box, 31 ... Free end, 32 ... Through hole

Claims (4)

An anode cylinder extending cylindrically along the central axis;
A plurality of vanes extending from the inner surface of the anode cylinder toward the central axis;
A spiral cathode disposed on the central axis;
A pair of end hats secured to both ends of the cathode;
A support rod connected to each of the end hats for supplying current to the cathode;
The magnetron is characterized in that at least one of the end hat and the support rod is made of a metal containing Nb.   The magnetron according to claim 1, wherein the end hat is formed of any one of Nb, Nb—Sn, Nb—Ti, and Nb—Ni.   The magnetron according to claim 1 or 2, further comprising a gas adsorbing metal other than the constituent elements of the end hat fixed to at least a part of the surface of the end hat.   The magnetron according to claim 3, wherein the gas adsorption metal is any one of Ta, Zr, and Ti.

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